0654 Co-ordinated Sciences June 2003CO-ORDINATED SCIENCES ............................................................................................. 2 Paper 0654/01 Multiple Choice ..................................................................................................................... 2 Paper 0654/02 Paper 2 (Core) ...................................................................................................................... 4 Paper 0654/03 Paper 3 (Extended)............................................................................................................... 8 Paper 0654/04 Coursework......................................................................................................................... 11 Paper 0654/05 Practical Test ...................................................................................................................... 12 Paper 0654/06 Alternative to Practical ........................................................................................................ 14 1 However. 35. The Paper is intended. As a consequence. The only question which candidates found particularly hard was 40. 30. the mark distribution tends to be skewed towards higher marks. primarily. 2 . to discriminate between candidates in the grade C to grade G range.2 with a standard deviation of 6. the Paper is also taken by candidates who achieve higher than grade C. Candidates would appear to have been well-prepared for the Physics part of the syllabus. 38 and 39. Physics questions which the candidates seemed to find relatively easy (over 70% facility) were numbers 28. There was a wide range of facility in the Biology questions. proved to be rather too easy since they did not discriminate sufficiently between candidates of differing ability. These values are satisfactory. however. 31. as they answered most of them well. This report concentrates more on the responses made by the grade C to G candidates.25. None was too difficult to make a valid contribution to the test with only Question 4 being answered correctly by less than 50% of the candidates. Three questions. Teachers and candidates are to be congratulated. 37.0654 Co-ordinated Sciences June 2003 Paper 0654/01 Multiple Choice Question Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Key D D B C B B B D B A D D B C C A C B B A Question Number 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Key D A B C A A D A C D D A D D B A A B A D General comments The candidates achieved a mean mark of 28. 32. however. Not only is this response the ‘wrong way round’ but it also ignores the instruction in the question for the SIMPLEST formula. Question 16 Overall. these questions were found quite easy by all candidates and this is gratifying. of course. that only 52% opted for the reverse of that situation (the correct answer). Question 23 Also slightly hard but with satisfactory discrimination. Question 22 A slightly hard question but one that discriminated very effectively. Only 2% believed that the blood in vessel Q had more urea and more oxygen than the blood in vessel P. this question allowed candidates to demonstrate some sound basic understanding of Biology. as the site of carbohydrate manufacture whilst failing to appreciate that the label was pointing to the cell vacuole. Question 4 There is the suggestion here that candidates did not exercise enough care in reading the question. the palisade cell. but it continued to serve two useful functions. Question 12 Although almost too easy to be of real value. Question 9 There was a basic misunderstanding in this question. 3 .0654 Co-ordinated Sciences June 2003 Comments on specific questions Question 1 This was one of the easy questions. this question was perhaps a little too confusing for some. is that oxidation and reduction occur together. Question 14 Again proving to be one of the more simple questions. Question 10 On the difficult side. There is never an intention to ‘catch out’ candidates. this question was found slightly hard but this was undoubtedly due to over half of the lower scoring candidates choosing D as their answer. this question did indicate that almost all candidates had a sound grasp of the principles of trophic interactions . therefore. This might imply either that they were guessing or that they were focusing on only one of the reactant/product pairs. Among the lower scoring candidates. It was surprising. albeit in a spongy mesophyll cell. The important point. It tested an important biological skill (the use of identification keys) and it made a welcoming start to the Paper for tense candidates. (or was it again a lack of careful thought?) since 39% of candidates suggested that carbon dioxide rather than energy is always released during respiration. were not deceived. Option C clearly indicated a chloroplast. “Read the question carefully” continues to be an important piece of advice. The lower scoring candidates tended to choose either B or C. Questions 17 and 20 By contrast. The better candidates. but there is a vital requirement on their part to read questions carefully.a topic that can sometimes reveal some surprising misconceptions. In fact 38% opted for region A. response A was rather popular and this is presumably due to confusion over whether barium nitrate is used to test for chloride ions or sulphate ions. but some candidates did not make it clear to which cell they were referring. which must be discouraged. Question 33 About two-thirds of candidates answered this correctly. then both must be repulsions. but a quarter thought that either amplitude or frequency changes during refraction. An increasing number of candidates are beginning to include the abbreviations they use in text messaging within their answers. Question 36 This was not answered correctly by as many as hoped. 4 . The problem was that most of these did not convert minutes to hours first. Many candidates found one or two of the questions quite difficult. A good spread of marks was achieved by the candidates. Question 34 In a similar manner. (a) (b) Some candidates were able to answer this using correct differences. clearly ignoring the instructions on the front cover of the Paper. Was this another example of not reading the question sufficiently carefully? Question 29 The vast majority of candidates knew that they had to divide distance by time. only half realised that 200m is a wavelength. Many managed to gain marks on all the questions. Many more spotted that four half-lives were involved. Some candidates lost the mark by referring vaguely to germs rather than infection. Comments on specific questions Question 1 A good spread of marks was achieved on this question. A small number of candidates wrote some of the answers in red ink. This is a trend. There was no evidence of candidates suffering from a shortage of time to complete the examination. being a typical example of a sedimentary rock. This was well answered by many candidates. Limestone rocks undergo weathering but they are not the result of weathering. and 36% simply assumed that since there was attraction in both the situations in the stem. Question 40 Half-life still causes confusion in the minds of many candidates. Candidates should know that metres cannot be a frequency. but only the most able candidates achieved full marks on any question. and candidates should be aware of the units in any question. bacteria or viruses.0654 Co-ordinated Sciences June 2003 Question 24 Similar comments as for Question 23 also apply to this question. Only one third answered this correctly. Paper 0654/02 Paper 2 (Core) General comments Almost all the candidates were able to attempt all the questions. Again. then when the metal rod is turned round. it was response A that was overly popular with the lower scoring candidates. Units are always important in Science questions. and simply multiplied by four. but almost as many thought that it is frequency. There were not many candidates who managed to gain all three marks here on what was basically a multiple-choice question. The only wrong answer commonly offered was potassium bromine. there was much confusion regarding differences. Many candidates gave a correct answer here related to the fact that potassium or metal ions were positively charged and therefore attracted to the negative electrode. These included differences in breathing and where the animals lived. Many candidates gained full marks. a number of candidates did not really understand the basics of electrolysis. Many candidates gained full marks.0654 Co-ordinated Sciences June 2003 (c)(i) (ii) HIV was generally well known. This was well answered. but their explanations were far from clear. Again. Irrespective of their answers to the last part of part (iii). Most candidates found it quite difficult especially in terms of describing whether the particles involved were moving or merely vibrating. Again some candidates were unclear as to whether the particles were vibrating before being heated. 5 . A number of candidates incorrectly answered in terms of claws. A few candidates unsuccessfully attempted to write out the full form of HIV. but few candidates appreciated that the hovercraft would suffer less wear and tear due to this low friction. This part was better answered. many candidates were unclear as to whether the particles were vibrating before being heated. Question 2 This question was only well answered by the more able candidates. This was acceptable. This part differentiated well. Some candidates suggested that it must be the negative electrode because brown fumes were being given off at the positive electrode. (iv) Question 4 (a) Whilst many candidates gained one mark here. The only common error was when candidates mentioned that elements contained only one atom rather than one type of atom. (b) (c) Question 3 (a) (b)(i) (ii) (iii) This part was well answered. Few candidates really understood the process of evaporation. (a) A number of candidates confused boiling and evaporation here. almost all the candidates knew that the ratio was 3:1. There was also a common misconception that the particles themselves expanded. Most candidates knew the genotypes but less knew the phenotypes and gametes produced. A number of candidates confused expansion and melting here. tails and length of tongue. Whilst many candidates were able to explain why strong heating was necessary. (b)(i) (ii) (iii) (iv) Question 5 (a) Most candidates were able to give an answer about less energy being used or the hovercraft moving more easily. Those who did not score maximum marks usually lost the mark(s) due again to vague answers mentioning blood or needles without giving sufficient detail. Some candidates gave an answer in terms of the involvement of delocalised electrons. Most candidates scored maximum marks here. There was also confusion as to whether the particles were already moving on a cooler day. A number of candidates mentioned that potassium was positive but did not mention that it was the potassium ion. This part was usually answered correctly. A few thought that fossil fuels were made from fossils. but a number were unable to explain this in terms of amplitude. others thought that photosynthesis was a form of respiration. Although most candidates had an idea that the length of the molecule was the crucial factor. some thought it made its own energy. A number of candidates confused amplitude and frequency. This was well answered. they were not able to describe this clearly enough to gain the mark. This part was almost invariably answered correctly. amplitude. few candidates mentioned a named substance. Although many candidates knew that a producer made its own food. Whilst many candidates were able to give correct answers in terms of single and double bonds. which showed a confusion between mass and weight but many wrong answers involved calculations using the area of the cushion. Many candidates got this right but many merely put the words magnetic and field into a sentence. Answers in terms of containing or not containing the maximum amount of hydrogen were also acceptable. The idea of respiration was not really understood by many candidates. This part was well answered.0654 Co-ordinated Sciences June 2003 (b)(i) There were many wrong answers here. (ii) (c) Question 6 (a) (b)(i) (ii) (iii) (iv) (c) Most candidates gained at least one mark here. This was well answered. A surprising number of candidates were unable to see the connection with the previous part. Whilst many candidates gained at least one mark for describing eating as the process by which energy is transferred in a food chain. some thought it only happened at night. Again there was confusion between. Some answers were 2000N. frequency and pitch. Most candidates identified the wavelength correctly. A straight line with arrowheads at both ends showed this clearly. which were confusing. Most candidates offered some suggestion but many were too vague to gain credit. Some gave answers. Many candidates tried to answer the question they wanted to be on the Paper about energy losses up the food chain. (ii) (iii) 6 . some gave very vague answers. showing excellent data handling skills. Most candidates realised that the sound was quiet. Question 7 (a) (b) (c) (d)(i) (ii) Most candidates gained full marks here. Question 8 (a)(i) (ii) (iii) (iv) (b)(i) Most candidates were correctly able to identify a suitable magnetic material. Either they knew the source of the fossil fuel or that it took millions of years to form. but few candidates did this successfully. which had no connection with previous part whilst others gave a value slightly greater than the previous part. All parts were well answered. A number of candidates used wavy lines or combinations of lines. There was much confusion here. Either they knew that the polymer molecule was large or they knew that it contained small molecules that had been joined together. predictably. Only the most able candidates gained two marks here. (a)(i) (ii) (b) (c)(i) (ii) (iii) (d) This was well answered. Even candidates who gave the wrong test in part (i) usually gave the correct colour change of purple. This was well answered. Some candidates tried to answer in terms of friction on the screen when the electrons hit it. (b) (c) (d) Question 12 (a)(i) (ii) (iii) (b) (c) Most candidates gained at least one mark here. 7 . Many candidates correctly gave two factors here. Most candidates scored one or both of the marks here. The least known element was nitrogen. even though many candidates found it difficult to spell chemotherapy. the common wrong answers. (a)(i) (ii) (b) (c)(i) (ii) Many candidates were either able to state that it was the biuret test or were able to state the reagents required. Although many candidates will have known that electrons are negatively charged they failed to state it. A common error here was to list the elements rather than the state the number of elements. Nearly all the candidates were able to draw the correct symbol for a voltmeter. Benedicts and iodine were. There were many different correct answers given here. but rarely both. with even the weaker candidates gaining good marks. the commonest answer was the kidney. Question 10 This question showed a wide range of marks obtained by the candidates. but there was confusion with acid rain and the greenhouse effect. Many candidates scored at least one mark here. Most candidates answered this correctly. showing a good understanding of the process of protein digestion. Analgesic was fairly well known. although voltage and current were common wrong answers from the weaker candidates. showing a wide range of knowledge of these metals. but many candidates failed to show on their diagram that the carbon dioxide had to be bubbled through the limewater. Most candidates appreciated that the glucose molecules needed to be joined to each other but many failed to suggest that the chain would continue on beyond the length of the chain drawn. Question 11 (a) This part was poorly answered. Most candidates realised that carbon dioxide was tested using limewater. but there were a number of popular wrong answers including aspirin and painkiller. About half the candidates appreciated that the voltmeter needed to be connected in parallel across filament. Most candidates gained one mark here. This was well answered by many candidates. This was well answered.0654 Co-ordinated Sciences June 2003 Question 9 A well answered question. Although some candidates knew the correct organ. candidates are getting better at showing their working for calculations. in general scoring better on part (a) than on (b). (b)(i) (ii) Question 2 (a) This was not easy. Part (iii) was answered very well by many candidates. Most were also able to state that the presence of petals was an indication that this is an insect-pollinated flower. one was awarded for some statement about the fruit itself (for example that it is sweet. Many candidates were able to deal competently with every question. indeed. Similarly. where some of the weaker candidates failed to read the information above it and wrote about ‘algae bacteria’ in their answers to (c)(i) and (ii). These candidates tended to draw diagrams of a whole plant. are not the same as a full formula. However. There was no evidence of any particular question being difficult for candidates to understand.not ‘excreted’ -. Of the two marks available. most candidates now take care to give either a balanced equation or a word equation as asked. but there is still a lot of confusion about pollen grains travelling down to the ovule. This part was very disappointingly answered by the majority. and many described the position or shape of the stigma or anthers also. or it is carried on the animal’s fur).0654 Co-ordinated Sciences June 2003 Paper 0654/03 Paper 3 (Extended) General comments As always. fleshy or has hooks) and the second for how this helps it to be dispersed (for example it is eaten and the seeds egested . Better candidates were able to state that this reduced competition. as many did. This was also found difficult by the weaker candidates. there was a very wide variation of performance on this Paper. or that it encouraged outbreeding by increasing the chances of unrelated plants growing near to each other. relating an increased temperature to increased pressure in their answers to (iii). many incorrectly gave 30 dm3. (a) The majority of answers to (i) were correct. significant numbers of candidates appeared not to have any experience of many of the topics from the Supplement of the syllabus that were tested here. although a useful aid. In general. and tried to use pressure = force/area. Quite a number described an advantage of animal dispersal (seeds are given a heap of fertiliser) which was not what the question asked. if they knew the formula P1V1 = P2V2. 8 . and that it enables the plant to spread to new areas. as asked in the question. with an animal eating a fruit from it. then wandering off to defecate somewhere else. then this frequently carries a mark. They should also realise that. it is very difficult to be sure exactly what is being labelled if the letter is perched on top of the diagram itself. and marks over 90 were not uncommon. Formula triangles. marks on Question 10 were often high. and many candidates struggled to work out the answer to (i). Comments on nectaries (none is visible) or on the pollen itself were not credited. apart from the graph in Question 7. At the opposite extreme. although weaker candidates often fail to do this in a way that is easy to understand. many others did not know this relationship. Comments on specific questions Question 1 Most candidates were able to make a reasonable attempt at this question. Unfortunately. although not all candidates did as asked and drew label lines. and. A surprisingly large number made no attempt to describe the structure of the fruit. they could still gain full marks on part (ii). Almost all candidates appeared to have finished the Paper in time. Other good answers included the idea that it avoided the whole species becoming extinct if there was a local disaster. though there were some good answers here and there. but there were still numerous examples of word equations in Question 3 (b)(i) and of formulae in 9 (a)(iv). The better candidates were then able to suggest that temperature may have changed. if asked to state a formula. (ii) caused more problems. (b) Question 4 (a) A surprising number of candidates were not able to answer (i) correctly. if they had given an incorrect formula for potassium hydroxide earlier and reused it here. Many did not know this. Acceptable answers included any of the noble gases and water vapour. or exacerbate global warming. and to state that this showed that heat was given off as the acid was added to the alkali. Other common errors included using NaOH instead of KOH. Some left the table blank. However. such as time needed for the breathing rates to adjust to the new concentration. and also remove the excess carbon dioxide quickly. Full marks were quite commonly seen. and stated that this is the point at which neutralisation has just been completed. Many were able to make a suitable suggestion for (i). and also for a specific example of how their use can lead to pollution. 9 . A few candidates gave gases which were already in the table. In (ii). Although most candidates were able to pick up at least one mark for the question. or that the peak in temperature shows the reaction has finished. Part (ii) was less well done. They were also able to read off the value of 22. (c) Part (i) caused little difficulty for most. Question 3 For many candidates. Full marks were common here. with many blindly trying to apply a formula they knew.or that they are more likely to have accidents. Those candidates who thought about diffusion had no problems here. but most did at least attempt answers. Credit was not given to answers which suggested that nuclear power stations always release radiation . they could still get full marks for this section. although a few misread the question and gave advantages rather than disadvantages. instead of seeing that all they needed to do was to multiply their answer to (i) by 0. Hydrogen was not accepted. as they were in (ii). and almost all candidates gained good marks on (i). that they produce carbon dioxide. (a) Almost all candidates were able to identify the temperature rise shown on the screen. with the majority getting it entirely correct. without saying what kind . (b) (c) (d) Question 5 (a) Marks were given in (i) for the idea that fossil fuels are running out. Quite a few tried to give an explanation relating to oxygen concentrations.0654 Co-ordinated Sciences June 2003 (b) This proved a much easier part of the question. who seemingly read the x-axis as if it were time. This was the most accessible part of the question. and for some comment on the relative flatness of the curve for the echidna compared with the man. Most also correctly gave a pH of 7 in their answer to (ii).25. and the better candidates gave three correct responses. writing KHO instead of KOH. Either words (hydrogen and hydroxide) or symbols (H+ and OH-) were accepted. However. Quite a few candidates lost a mark here by stating only that ‘they cause pollution’. or for the carbon dioxide concentration to reach the same level all over the room. or cause acid rain. at higher carbon dioxide concentrations. A few even suggested potassium and chloride. Marks were awarded for stating that the echidna’s breathing rate did not increase as much overall.for example.5 cm3 from the graph. and gave hydrogen and oxygen. Only a very few misunderstood how this sensor works. Part (ii) also proved not to be as easy as expected. This part proved more difficult. and that increasing the breathing rate could supply more oxygen for this. with some very strange suggestions relating to magnetism and other phenomena. and was often answered entirely correctly.though radiation leaks were accepted . or thinking that hydrochloric acid has the formula HCl2. marks were available for the idea that a raised blood carbon dioxide concentration could be an indication of increased respiration in the tissues. Parts (ii) and (iii) were often well answered. part (ii) was difficult for many candidates. there were quite a few instances of word equations being written. or produce sulphur dioxide. this was their best question on the Paper. Thus answers such as ‘the man’s breathing rate increases more rapidly than the echidna’s’ were common. but many did not. though. and others explained that the reaction is reversible. and some did know this. marks were awarded for explaining that the numbers of algae increase close to where the fertiliser flowed into the river. and hence the fall in fish numbers. and wrote about ‘algae bacteria’. the latter most often for explaining that the fish died (or moved away) because of the oxygen shortage. Even those candidates who knew that sulphuric acid should be reacted with the ammonia solution could often go no further than that.testing for it. although some of the better candidates could name at least two of oxygen (or air). Many. and how to evaporate water to leave crystals were relatively rare. rather than . many answers suggested that plants could not absorb gases. Better candidates explained that the plants would use the nitrogen compounds to make proteins. Part (ii) was not well known. showing a good understanding of the process of eutrophication.or as well as . and did not gain any marks at all. so that without its presence the percentage of ammonia obtained would be lower. or increase the yield. and. This. All sorts of complicated answers relating to the nitrogen cycle appeared in (i). A mark was also available for the suggestion that the soil might be short of nitrates. These candidates suggested that it was the algae which were responsible for using up the oxygen. weaker candidates struggled to make any correct statements in their answers to either (i) or (ii). how neutrality would be indicated. and then decrease downstream where the fertiliser has been diluted or used up. the question was worded carefully to guide candidates towards thinking about bacteria. Many candidates knew that not all of the nitrogen and hydrogen would react in the reaction vessel. A few looked only at the graph and not at the information above it. Most could answer (ii) correctly. In (ii).0654 Co-ordinated Sciences June 2003 (b) Both parts were often correctly answered. although there were a few instances of candidates getting the numbers back to front. Many had no idea about how this could be done. along with descriptions (usually incorrect) of how the ions would be transported within the plant. This part of the question was less well answered than the previous sections. or missing a 0 somewhere and therefore ending with an answer of 5:8. They also knew that the catalyst speeds up the reaction. with (ii) proving a little more accessible than (i). Some candidates answered this very well. A surprising number described ways of generating ammonia. However. Some candidates knew about active transport and this was credited. but this was relatively rare. which turns blue. thought that this occurs by osmosis. too. In (i). was disappointingly answered. and correct descriptions of mixing until neutral. many simply guessed. which produces white ‘smoke’ on contact with ammonia. or that nitrogen was not soluble. by diffusion. Both parts were well answered. This was very disappointingly answered. The expected answer to (i) was that the voltage is stepped up as this minimises energy losses as the electricity is transmitted from the power station to its points of use. (b) (c) (d) Question 7 (a) This was another question which was surprisingly poorly answered. However. simply suggesting that the plants need nitrogen to grow. and this would increase their rate of growth. (b) (c) 10 . most answers were much more vague. but many completely failed to mention them. The expected answer was that the ions would be taken up into root hairs. The expected answer to (i) was that nitrogen gas is unreactive. water and a named catalyst. Some even suggested that nitrogen molecules were too big to fit through the stomata. Some candidates correctly described using hydrogen chloride gas. There were many good answers scoring full marks. but many with zero or one. Xylem did occasionally appear as an answer to (ii). Question 6 (a) The test most frequently given was using damp red litmus. and making good use of the information provided in the graph. However. Part (iii) was usually well answered. Part (i) was usually well answered. with good explanations being given in terms of the charges on the positive palladium ions and the negative chloride ions needing to balance to form a neutral compound. or to give incorrect units in the final answer. Part (ii) required a little more mathematical skill. or to include just temperature. In most Centres all the tasks set were appropriate to the requirements of the syllabus and the competence of the candidates. The most common errors were to fail to give the full formula. and not all could cope with the square and square root. which was not acceptable. and full marks were frequently awarded. and to give incorrect units in the final answer. This was well answered. (b) Question 9 (a) A wide range of sources for methane were accepted. However. Some Centres had introduced cue cards to help weaker candidates. as was (iii). Several tried to use momentum or force in the answers. If (i) had been answered incorrectly. not all then answered (ii) in terms of energy. with (a)(ii) proving the most difficult section. despite the question clearly stating that they should they should use their answer to (i). Most have provided coursework in previous years and have acted on advice given. marks were given for stating that the voltage would remain unchanged. and some suggestion of what might be done to avoid harm if it were to be detected.0654 Co-ordinated Sciences June 2003 Question 8 (a) Most answers to (i) were correct. the most common error being that switch B would be off in the last row of the table. Part (iv) proved very difficult. and could still gain two marks for this if they used this answer in the correct way. The most frequent errors were to convert the mass of the car into a weight. Part (ii) was usually well answered. Candidates’ work covered the whole mark range with the impression that the mean was higher. such as leaving the room or opening some windows. (a) Part (i) was very well answered. though some of the weaker candidates simply wrote ‘It would be unchanged’. In only one Centre was there some minor confusion about a few tasks. (b) Paper 0654/04 Coursework General comments Nature of tasks set by Centres This year 19 Centres submitted coursework for the June examination. but many could not answer this. which was not accepted. Most candidates knew that KE = 1/2mv2. and for stating that the current flowing through the motor would be less. (b) Question 10 This question was often high-scoring. 11 . Marks were awarded here for the idea that carbon monoxide is harmful to humans. Some work was outstanding. Part (iv) was also often correct. Some candidates had problems balancing the equation. A few gave formulae instead of words. rather than temperature change. and were able to use this to carry out a pair of calculations (usually suggesting a value for the mass of the car) and then show that one value was 4 x the other. Part (iii) was also quite well done. In (ii). voltage and charge. that we cannot detect it with our own senses and therefore need a detector. and a few failed to answer this at all. with most candidates able to quote the formula F = ma and then substitute into this to obtain an answer of 4 m/s2. although some good answers were seen which provided an explanation related to the relationship between energy. suggesting products such as propene or propane oxide. candidates were allowed to take their wrong answer forward into (ii). The standard of candidates work was of a slightly higher standard than previous years. Part (ii) was often well answered. although a few candidates did not know what was meant by a displayed formula. or that the voltage drop across the motor would be less. (a) Most stated that the test-tube became warm although a small number thought it became cool! It was necessary in part (ii) to record an appropriate observation of water such as condensation or drops on the side of the tube. Many Centres have developed a booklet of tasks and dedicated assessment criteria. There were few very poor candidates. Recording of marks and Teacher’s annotation Following suggestions made encouraging the use of annotation on candidates’ scripts many more Centres are using this technique to indicate or justify marks awarded. There is still scope for further improvement with some Centres writing comprehensive summaries but not indicating the point at which the mark was awarded. Only one Centre (new to the scheme) tried to assess both skill C1 and C4 in the same investigation. A wide range of colours was accepted such as red. Even the obvious ‘no burning’ mark was not scored by many. all of whom played their part in the provision of these results. where candidates have to suggest a further experiment or devise a plan for performing an unfamiliar task. (b) (c) (d) 12 . Good practice Some Centres make very useful comments about individual candidate’s performance on a summary sheet. Most were able to identify the conversion to a sugar and consequently answer yes to part (iii) and make some deduction as to how the sugar was formed. A statement that water was produced did not count as an observation. Sufficient time is given for these problems to be identified before the candidates start their test and difficulties of this kind should be dealt with. A few Centres provided help cards to enable candidates with difficulties to proceed. green and yellow. Advice has been given to help the Centre avoid confusion in future. a mark was sometimes lost by recording no change when solution A was tested. Most appeared to know the test for starch and scored two marks although few gave a full answer in terms of what would happen if no starch was present as well as the observation if starch was present. Many Centres have developed very comprehensive recording systems. Paper 0654/05 Practical Test General comments There were some very good answers and evidence that many candidates were well prepared for the examination. However. A few Supervisors reported problems with testing for protein. The results for Question 3 relied upon Supervisor’s results. Two Centres introduced spreadsheet format to summarise all candidates’ marks across all assessments. In contrast. It was particularly good to see that there is improvement in answering the planning part of a question i.e. All marks were used and the mark scheme produced a good spread. Excellent. Part (iv) was usually correct but (v) less well answered.0654 Co-ordinated Sciences June 2003 Teacher’s application of assessment criteria In nearly all Centres the assessment criteria were understood and applied well for all of their activities. Comments on specific questions Question 1 This question was very well done with many candidates reaching a maximum or near maximum mark. The majority correctly identified carbon dioxide. Question 3 was the least well answered. part (vi) was well answered. Tick lists remain popular with particularly skill C1. Adding a blue solution to a colourless one does produce a change. There has been a steady improvement in the Centres’ application of assessment criteria. A high percentage of candidates did this test correctly and identified B as the protein. This made it difficult to answer parts (c) and (f) correctly. The most common observations were. All such answers were treated as correct. this was probably guesswork for some. The value of the potential difference alone is insufficient to correctly answer this question. Consequently the scale did not permit such a reading. The explanations were less well described. Very few mentioned the transfer of electrons that was required for the second mark. Many correctly stated magnesium for one mark but few understood why.0654 Co-ordinated Sciences June 2003 Question 2 (a) Almost all candidates were able to perform the experiment and collect five sets of readings. bubbling. The graphs were very well done with few awkward scales and few reversed axes. Many thought the gas oxygen was evolved! Candidates struggled here. Some recognised displacement and some realised that copper was being formed. A good number did not make use of the origin and a mark was lost if the line did not or would not pass through the origin. A large number scored two marks by correctly stating that the force was directly proportional to the extension. Apart from a penalty mark this did not affect the rest of the question. Providing the existing line was used. Many calculated it by taking a combination of readings. Some did not have the ruler with the zero at the bottom therefore producing a set of negative values for the extension. No mark was awarded to those who simply stated that the extension increased with force. Many scored all three marks for these values. Some were more intent on trying to calculate a spring constant. Using the former was really out of order as no solutions of the cations were mentioned. the question asked for a straight line and the majority obliged.2V of the Supervisor’s values. A popular choice was to use the displacement experiment rather than the measurement of potential difference. brown or black solid produced and a rise in temperature. Although the points were sometimes scattered.5N was required. It was necessary for the recorded voltage values to be within 0. Most stated the correct order. The expected method was to repeat the experiment of measurement of potential difference with each pair of metals. colour fading. many were able to score three marks. very few managing to score three marks. It all hinged on appreciating that it was the negative terminal when connected to zinc and copper and the zinc was the negative when connected to copper. Some were caught out by not reading in advance that the extension for a force of 3. A mark was deducted if the line did not pass through the origin. noting the voltage and particularly which metal was the negative. Almost always a suitable line was drawn. Some lost a mark by either not indicating how the force was converted into a mass or incorrectly indicating how this was done. Marks were lost for such errors as a wrong force or extension value in centimetres rather than millimetres. (a)(b) Although many scored a mark for the negative metal in each case. (b) (c) (d) (e) (f) Question 3 Many candidates did not understand this question and certainly failed to appreciate that it was necessary to concentrate on the direction of electron flow. (c) (d) (e) (f) 13 . which was acceptable in view of the linear nature of the graph. The most common error here was the failure to recognise the use of the line already drawn. Only a small minority of candidates achieved full marks. Alas. This is made clear in the following comments on individual questions. Otherwise. Comments on specific questions Question 1 This was mainly well answered. the potential differences shown for Mg . Some candidates also mentioned environmental factors here instead of in part (d). Study of the mark scheme will reveal how the Examiners awarded intermediate marks. Many candidates incorrectly tried to relate speed of transpiration to shoot thickness and xylem vessel diameter rather than to the area of the leaves or to stomatal density. possibly because most had never seen a potometer experiment carried out. still using this experiment. Study of Fig. (a) Most candidates constructed a neat and comprehensive table. including the ubiquitous global warming! The underlying fault lay in the failure to relate to the laboratory conditions of the potometer experiment. if correct total distances were divided by an incorrect time. Many candidates added up all the distance readings and then divided the total by nine.2 will reveal how this anomaly is still entirely acceptable. in the headings. (b) (c) (d) Question 2 This question was based on a corresponding question in the Practical Examination. This preparation must include certain minimum elements: the first. Four marks were possible for finding the average “water loss” in cm/s. for example. always “more negative” than the others. 2. Others simply gave an answer and showed no working. 14 .0654 Co-ordinated Sciences June 2003 Paper 0654/06 Alternative to Practical General comments The Examiners are pleased to report that there have been fewer very poor candidates than in previous years and that the overall quality of Papers has been improved. The Paper seeks to test these two areas above all. Some omitted the units cm. though in recording the data some omitted the zero readings of the meniscus. s. choosing to refer instead to the area where the plant might grow naturally. To prevent entirely mathematical answers. A few tried to draw graphs instead of a table. with correct headings and units. would lead candidates to the obvious (and simple) conclusion that the more reactive of two metals will be the one that must be connected to the negative terminal of the voltmeter to show a reading. The explanation should also refer in some way to evaporation of water from the leaves. is sufficient laboratory experience and the second is adequate practice in problem solving using experimental results. this was rarely the conclusion drawn by the candidates.Zn and Zn . and mere learning of scientific fact is rarely enough to gain a good mark. they explained that the magnitude of the potential difference between metals showed how dissimilar they are in reactivity.Cu did not add up to that for the Mg . since the voltmeter on the left is showing its maximum reading. though the logic of deriving (c) from the answers to (a) and (b) escaped those who did not know that magnesium is the most reactive of the three metals.Cu couple. and this led to errors in (b). A wide variety of environmental factors controlling evaporation from the leaf were suggested. the number of readings. Centres are to be commended for their good preparation of candidates for the Alternative to Practical examination. (d) Examiners hoped that magnesium. (a)(b)(c) Most candidates scored well in these parts of the question. (a) (b) A few candidates recorded the heights h3. (a)(i) Candidates were required to complete the table referring to the combustion of bread. Others did not read the scales and tried to calculate everything. “Linear” was not acceptable. The word “proportional” or a related word had to be used to describe the relationship.0654 Co-ordinated Sciences June 2003 Many candidates preferred to rely on chemical reactions such as displacement of one metal by another or of hydrogen from an acid. The straight line had to pass through the origin to gain all three marks here. The conclusion that the reaction is exothermic was not always drawn. rather inaccurately read off the values and then filled in the last column. (ii) (b)(i) (ii) (c) Question 5 Some candidates found an unintentional source of confusion between parts (a) and (c) of this question. the sequence of colours observed is usually green . Question 3 Many candidates who did not study the description found this question too difficult. Some drew a straight line on the graph beginning with the data already given.red and the product is the red copper(I) oxide. It should be common knowledge that zinc and copper do not react at room temperature with water. and such connections should be emphasised.height) did not know how to complete the last column of the table. This proved a problem for many candidates who had learned the food test by rote. This reaction provides a nice link between biology and chemistry within the syllabus. Alas. The test for starch. When “reducing sugars” react with alkaline copper(II) solution. Most candidates seem to have learned that a positive response to Benedict’s test is an orange colour. These two processes could be described in other words for the two marks awarded here. Candidates who understood the experiment often gave elegant answers to this question and showed how to convert the extension in mm to mass in g or kg. the usual confusion between mass and weight showed itself in other candidates’ answers. This elicited many responses that were partly correct but not the scientific answers that are sought at this level. Others did not seem to know that enzymes are proteins. Others read the scales “inverted”. for instance “Our cells do not burn up” or “heat is not given out during respiration”. as they did not know that biuret reagent is a blue solution. Many candidates wrote that the red colour observed showed that the mixture was acid. but they knew that the copper(II) complex formed is purple. Very few candidates gave a correct answer to this question.orange . h4 and h5 in the wrong column.yellow . Most candidates knew the limewater test for carbon dioxide. (a)(i) The crystals dissolved and the particles diffused. was well answered. and others recorded the heights in centimetres. either aerobic or anaerobic. Those who did not realise that extension = (270 . The Examiners did not accept answers based on differences in reactivity with water unless heating was mentioned. which takes place in both (a) and (c). 15 . Acceptable answers included some reference to respiration as a slow enzyme-controlled oxidation of glucose. (b) and (c) are based on a beautifully simple experiment that demonstrates all the colours of Universal Indicator in one test-tube. potassium manganate(VII) must be present in the tube with calcium hydroxide! The connection between the parts of the question lies in the diffusion of the solid into the water. where two very different solutions are both described as purple. A few candidates inferred that in (c). (c) (d) (e) Question 4 This and the preceding question were based on the corresponding practical questions in Paper 5. 0 g and 15. Answers involving the use of a displacement can were also accepted. The Examiners realise that two different answers for (b)(ii) are possible.” In this case. were accepted. Only the answer 55 cm3 was allowed. The Examiners did not expect the correct name for the salt of ethanoic acid. since not only had neutralisation occurred but also more calcium hydroxide had dissolved so that it was now in excess. Some candidates incorrectly suggested that a catalyst could be added. 15. was added or that only a small amount of the solute was present in a large volume of solution. though “neutral” gained one mark. or to “Place 50 cm3 of hexane in the cylinder. “Not concentrated” was rejected. 16 . “(b) and (c)” was rejected as not specific enough. failed to correctly calculate the masses. A minority of candidates. The answer looked for was “(b)(i) and (c)” but a description of the necessary results. since there are many bases that are insoluble in water and so would give a neutral reaction. Both answers. “The ethanoic acid had been neutralised by the calcium hydroxide” was the accepted answer. heating and crushing the crystals are the ways of speeding up the processes in (i). in this case water. The only answer accepted was “alkaline”. This was harder. the addition of the sodium chloride would take the total volume into the ungraduated section of the cylinder or cause the hexane to spill. but far too many candidates began their answer with an instruction to “Fill the measuring cylinder with hexane”. but some candidates provided it.2 g. This was often well answered. depending on which way the subtraction is done. Answers such as “The solution was still alkaline” or “The acid had not reached the calcium hydroxide” were rejected. as was an equation providing any recognisable name for a salt formed at the same time as water. mass of the solution and its volume was given the mark. Some candidates wrote that the colour of the indicator shows that calcium hydroxide is basic. The Examiners looked for the idea that a solvent. The general equation “acid + alkali → salt + water” was an acceptable answer. (a) (b) (c) (d) (e) Most candidates scored the three marks available here.0654 Co-ordinated Sciences June 2003 (ii) (b) Stirring. but still a surprisingly large number. (c)(i) (ii) (iii) (iv) Question 6 This was a straightforward question in which candidates had to read balance windows and the scale of a measuring cylinder and manipulate the resulting figures.